Malignant pheochromocytoma in a pig.

Endocrine tumors are rarely observed in pigs, and pheochromocytomas have been only punctually described. The current report describes a white and firm, 15-cm in diameter, neoplastic mass located in the adrenal gland with metastasis to regional lymph nodes in a 2.5-year-old sow. The masses had marked desmoplasia that supported a population of polygonal-to-spindle-shaped neoplastic cells arranged into cords and packets within a delicate fibrovascular stroma. Immunohistochemical staining of the tumor was positive for chromogranin and negative for neurofilament protein in adrenal and lymph node masses, which was characteristic of a malignant pheochromocytoma.

Histidine Decarboxylase Activity of Enterobacter cloacae S15/19 during the Production of Ripened Sausages and Its Influence on the Formation of Cadaverine.

The histidine decarboxylase activity of Enterobacter cloacae S15/19 was studied during the production process of salchichón , a Spanish ripened sausage. Counts of fecal coliform and histidine decarboxylase bacteria decreased during the production process, showing a good correlation in both inoculated and control samples. In the samples inoculated with Enterobacter cloacae S15/19, fecal coliforms were undetectable the last day of the survey, while the population of histidine decarboxylase bacteria was over 2 log MPN/g. Despite the fact that inoculation with Enterobacter cloacae S15/19 increased histidine decarboxylase bacteria counts, no differences were observed in the histamine concentration reached, which was undetectable in most of the control and inoculated samples. In contrast, cadaverine concentration increased significantly (P < 0.01) in the inoculated samples, suggesting that cadaverine could be used as a hygienic-quality indicator of the raw materials employed in sausage processing.

Sensory Quality and Histamine Formation during Controlled Decomposition of Tuna ( Thunnus thynnus ).

Histamine production was studied during controlled tunafish decomposition at 0, 8, and 20°C. The influence of the location of the anatomic section on the amount of histamine formed and the incidence of histidine decarboxylating bacteria were also considered. By the time of sensory rejection, histamine levels in tunafish sections stored at 0 and 20°C were still below the hazard levels and the allowable levels established by both the U.S. Food and Drug Administration (FDA) and the European Union. Toxic amounts were only formed after the tunafish was considered organoleptically unsuitable for human consumption. However, at 8°C, levels of histamine between 100 and 200 mg/l00 g of fish were found before tuna reached the rejection point. Hence, physical appearance was not a good criterion for estimating the shelf life and especially the histamine-related health hazard when tuna was stored at 8°C, a common temperature in many home refrigerators.

Histidine Decarboxylase Activity of Bacteria Isolated from Raw and Ripened Salchichón , a Spanish Cured Sausage.

Twenty samples of raw sausages (before the ripening process) and 10 of ripened sausages of two different sizes of salchichón , one of the most-consumed ripened meat products in Spain, were microbiologically analyzed. Histidine decarboxylase activity of different isolates obtained from different culture media was evaluated by a decarboxylase agar medium and confirmed afterwards by an enzymatic method. Of the isolates obtained from raw sausages, 15.8% showed histamine-forming activity, most of them (78.1%) belonging to the Enterobacteriaceae family. Klebsiella oxytoca , Enterobacter aerogenes (one isolate), and Enterobacter cloacae (six isolates) showed a powerful histamine-forming activity, producing more than 3,000 µg/ml. In spite of histamine-forming activity being detected in eight of ten analyzed samples of ripened sausages, only one histamine-forming bacterium, identified as Lactobacillus curvatus , was isolated; it showed an ability to form 1,994 µg/ml of histamine in experimental conditions.

Bacteriological Quality of Tuna Fish ( Thunnus thynnus ) Destined for Canning: Effect of Tuna Handling on Presence of Histidine Decarboxylase Bacteria and Histamine Level.

The present paper analyzes the bacteriological quality and histamine content of tuna fish samples destined for canning. Raw material used in the canning process was of good quality. Histamine-producing bacteria counts were only found in three samples from the last step of the canning process before sterilization. Most of the bacteria identified as histamine formers were gram negative, and nearly all of which belonged to the Enterobacteriaceae family. Morganella morganii was the most frequent and active histamine former in tuna fish destined for canning. Other powerful histamine-producing bacteria isolated during the canning operation were Klebsiella oxytoca , Klebsiella pneumoniae and some strains of Enterobacter cloacae and Enterobacter aerogenes . They all were able to produce more than 500 ppm of histamine in experimental conditions. Most of these species might be expected to be found as a result of contamination of fish during capture and subsequent unhygienic handling in the canning plant. An increase in histamine content in tuna meat was not expected through the canning process. Histamine content always was acceptable in accordance with the maximum allowable levels of histamine fixed by both the European Economic Community and Food and Drug Administration.